And the starting QB is …

Beats me. Interim coach Jim Tomsula will probably announce it today .. or you would hope so after the 49ers misplayed the game of cat and mouse like no team in NFL history.

Here’s one vote for David Carr to make his first start of the year.

Why, you ask (other than the obvious ties to Fresno State)?

Alex Smith’s ship has sailed, and he won’t be coming back to his bay’s shore. The former No. 1 overall draft pick has privately told those around him he won’t come back when his contract expires after this season — of course, that was before coach Mike Singletary was fired, and who’s to say the 49ers would have had him back?

Starting Alex does nothing to help the 49ers decide their future at quarterback. They know what they have in Alex, and nothing he does Sunday against the Cardinals is going to change that.

They also know what they have in Troy Smith, who has been rendered mostly ineffective the past four games since defenses. He’s already beaten Arizona once, so what does he prove doing it again?

Troy is a restricted free agent who could be brought back on the cheap. The next GM and coach don’t need another game tape to make that call.

What the 49ers don’t know is what they have in Carr. Singletary saw to that by letting Troy bypass him on the depth chart after one half played in Carolina … in a game where he was thrown in unannounced after Alex separated his shoulder, and after getting zero first-team or scout-team reps in two months. What did they expect other than his 5 for 13 day?

They are going to draft a quarterback of the future. Why not start Carr on Sunday and see if he’s worth keeping around as a veteran to keep the seat warm or serve as a Trent Dilfer-like mentor? Cleveland and Arizona tried to sign Carr in the offseason but Singletary convinced the Bakersfield native he would get a fair shot if he came home.

They already know what they have in the Smiths. May as well see what Carr brings to the table.

And, for those who will clamor for Nate Davis, it’s too late. Practice squad players cannot be promoted to the active roster in the final week of the regular season, I’ve been told by an NFL executive. The kid isn’t an option this week.

If you’re wondering why Davis wasn’t promoted in time, remember that Singletary didn’t get fired until after Game 15 and he simply wasn’t having Davis.